The present invention relates to a hinge assembly for rotatably coupling first and second members together, and more particularly, to a position holding, self-latching hinge for holding first and second members at any specified angle of rotation relative to each other and which provides an additional latching force at a specified angle of rotation.
In certain hinge applications, it is often desirable to control the angular position of a first member which is rotatably coupled to a second member by using the hinge itself for both rotatable coupling and positional control. One such application is for the field of laptop, notebook and palmtop computers in order to allow a user to rotatably position the liquid crystal display screen at a selected ergonomic viewing angle.
In a notebook computer, the liquid crystal display is typically connected to one side of a friction hinge assembly and the base of the computer is connected to the other side. The display is held in any angular position by frictional torque generated by the hinge. One preferred hinge arrangement is disclosed in U.S. Pat. No. 5,491,874, which is assigned to the assignee of the present application and which is incorporated herein by reference as if fully set forth.
The presently known notebook computers generally include some form of latching mechanism. For example, a pair of latching mechanisms 11 can be located at the sides of the display 17, as shown in FIG. 1, or a single latching mechanism 14 can be located at the top of the display 17, as shown in FIG. 2. These latching mechanisms are required in order to maintain a minimum gap between the display 17 and the processor housing 18 of the computer 10 at all times during storage and transportation to prevent inadvertent opening of the display 17. When the computer display 17 is rotated downwardly to the closed position, as shown in FIGS. 3 and 4, either the pair of side latching elements 11 are engaged in receiving slots 12 shown in FIG. 1, or the front latching element 18 is engaged in the receiving slot 15 shown in FIG. 2. In order to open the computer display 17, the user must either slide both latching elements 11 toward the front or rear of the computer while rotating the display counterclockwise, as indicated in FIG. 3, or unlatch the latching mechanism 18 by pressing downwardly or inwardly to release the mechanism 18 while rotating the display upwardly, as shown in FIG. 4. In both cases, the user must actuate one or more latching mechanisms prior to opening the display.
One problem with the known latches is that they are easily broken and have a relatively short life. This often means that broken latches must be replaced by the manufacturer or the purchaser one or more times during the notebook computer's life. Additionally, due to the larger size display screens which are becoming available for computers, it would be desirable to eliminate the need for latches either at the sides or center of the display in order to utilize that space for a larger display without the need for increasing the overall size of the computer housing. Additionally, it would be beneficial to decrease the complexity and cost of the display bezel by eliminating the need for separate latch mechanisms altogether.